Process of reproduction in flat and offset printing



06L 1957 w. NEUGEBAUER ETAL 2, ,3

PROCESS OF REPRODUCTION IN FLAT AND OFFSET PRINTING Original Filed Jan.13, 1949 IN V EN T 0R5 I I141 HEzM WEl/GEBAl/ER PROCESS OF REPRODUCTION1N FLAT AND OFFSET PRINTING Wilhelm Neugebauer, Wiesbaden-Biebrich, andJak ob- Barthenheier, Eddersheim-am-Main, Germany, assignors, by mesneassignments, to Az oplate Corporation, Summit, N. J., a corporation ofNew Jersey Original applicationiJanuary 13, 1949, Serial No. 70,804.

Divided and this application March 2, 1956, Serial No.

8 Claims. 01. 101-149; g

Foils having a hydrophilic surface photo-sensitized by means of diazocompounds have already been proposed for use in flatand'otfsetjprinting, An effective method consists in producing a layerof regenerated cellulose on cellulose ester-foils, e. g." bysuperficially saponifying the ester-foil, applying a photo-sensitizingsolution containing suitable diazocoinpounds to the cellulose layer andfinally exposing the light sensitive foil to light under an original,thereby transforming the diazo compound at all places Patented Oct. 22,1957 Figure IV isa view in diagrammatic elevation showing the article ofFigure III exposed to the light to transform thephoto-sensitized surfacein the areas not protected by the mechanically transferred image into ahydrophilic surface and decompose the diazo compound underlying themechanically transferred imageinto a printing ink re-" ceptivesubstance, and i Figure V'is a view in diagrammatic elevation showingthearticl'e of Figure IV having the colloid substance re-.

moved therefrom to give'a printing ink receptive image.

The basic material 2 shown in Figure I is provided with a hydrophilic'surface 4 photo-sensitized with 'a'diazo I compound which on exposure tolight will decompose into In FigureII,

a mechanically transferred image 6 is applied to the hy-" I drophilicphoto-sensitized surface 4. The areas of the a fatty printing inkreceptive substances.

7 photo-sensitized surface not protected by the mechanically transferredimage are then transformed into hydro- 7 philic areas.

As shown in Figure foil vis coated with a solution containing watersoluble "colloid substance. The solution containing the hydrocolloid isaccepted at all other areas to form a coating 12 "on the foil.

philic colloid substance is repelled at all areas 6 of the foil Whichare covered by the mechanically transferred image since theseareas havehydrophilic properties. The

If now the foil is exposed to light as 'shown in Figure IV, either onits front surface as shown, or in the eventthe foil is sufficientlytransparent, on its back surface, the diazo compound is transformed intoa hy- .drophilic reaction product 8, wherever it is covered by where itis not -covered by the originaltand therefore i influenced by light)into a decomposition product having At all places which ready acceptancefor fatty inks. were'protected from directexposure toylight, the foilpreserves its 'hydrophilic property and repels fatty ink.

Thus positive prints are obtained, if negative originals are used.-This' known process is a photochemical one. 1 One object of our presentinvention is to' provide a process of reproduction ip flat and offsetprinting which uses as a starting material foils of the above describedkind,

i. e.-foils having l iydrophilic, non-metallic surfaces and .5; lightsensitivelayers containing diazo compounds'assensi 1 tizing agent, andtransforms this foil intoa positive 'print' ing plate without aphotographic printing step; I

The process of our invention is carried out v by mechanicallytransferring the image which is to be reproducedonto the sensitizedfoil,e. g. by printing, .writing or drawing. I

At'allplaces where it was not protected by the transferred image thediazo compound is then transformed into a 'hydrophilic reaction productwhich is no longer light sensitive .and will no longer couple withazocomponents. Finally the diazo compound covered by the transferred imageis decomposed by exposure to light into a product which will acceptfatty inkr when wet. It is to be underadapted to improve the supplenessof the coatings formed.

stdodi 'thatftlie latter exposure to light is carried out without theinterposition of an original.

The above'mentioned objects .of the invention 7 and method of itsattainment will be more fully understood by the following descriptiondrawing in which:

Figure I is a view in diagrammatic elevation shQWingtheQ base materialhaving a hydrophilic surfacefphoto-sensi Figure II is a view indiagrammatic elevation. showing; 1v

the base material as in Figure I but with an image metized means of adiazo compound,

chanically applied thereto, 7

Figure III is a view in diagrammatic "elevation showing the article inFigure II with a colloid substance applied thereto to cover the areasnot. protected by the mechanically e ef jt e mase taken inconnection'witli the the colloidal substance 12, i. e. at allplaces'which are not protccted'by the mechanically depositedreproduction, of

the image'ti. At all areas 10 of the foil, which are situated under thematerial making up the deposited image 6,

the diazo compound is converted by the light into a "decomposition"product which has hydrophobic properties and readily accepts fatty ink.

Suitable water soluble colloid substances are gum arabic, celluloseethers, polyuronic acids and their salts,

dextrine, sugar, polyvinyl alcohol, the polyvinyl 'pyr rolidones, watersoluble urea resins, solutions of protein substances,.polyethyleneoxide, pectin, sodium alginate,

hydrogum, 'guar resin, the polyphosphates, e. g. sodiumhexametaphosphate and others. Guar resinis defined in the Journal of theAmerican Chemical Society, vol. I: (1948), pages 2221 and 2222 aspolysacchoxide (mannagalactan). Hydrogum, is the commercial name used bythe Harris-Seybold Company for the mesquite gum These substances can beused alone or in which it sells. combination with each other and/ orwith other substances A neutral or weakly acid reaction of the solutionof the colloid substance often improves the effect of the invention.

The usual printing colors, lithographic inks and pencils can be used fortransferring the image 6 onto the light sensitive foil by printing,writing or drawing. The depo sition ofthe picture upon the foil can alsobe accom- I plished by means of a typewriter provided with the normaltypewriter ribbons. The content of coloring matter in the printing inkis not of anyimportance, because the inks Qi- QWFPFQ UQEQ in certaincases, because the. exposure deposited upon the light sensitive foil forthe purpose of producing the image in question has as its primarypurpose the repelling of the solution of the colloid substance from iall areas 60f the foil appertaining to the image,

Hence-it follows, that the inkused'for. producing the image 6 on thefoil must not necessarily be colored. A printing substance or printingink which in the course of the exposure does not absorb at all, orabsorbs only weakly, the light which is actinic to the diazo compoundIII for this purpose, the imaged front surface, whereas printing inkshaving high absorption for this actinic light make it desirable, if notnecessary, toexpose the foil to the light onuits back surface.

In this case the. foil must have suflicientlight transmis,

sibility.

Foils or bases 2 which can 'be used for the new repro-'- duction processare foils made of cellulose esterswhtc'h are transformed to regeneratedcellulose by means of saponification to a depth of about -2Qu. Foilsproduced from polyvinyl esters or similar saponifiable plastics andhaving saponified surfaces canalso be used. A modification of the methodconsists in applying the esters or other saponifiable plastics in theform of a lacquer to a base, such as a sheet of metal or paper or thelike, and superficially saponifying the lacquer coat.

Furthermore, it is possible to back the foils with sheets of metal,plastic material and other substances. This modification of the processis. to be recommended, if the foils have been made of regeneratedcellulose, which foils do not have a satisfactory dimensional stabilityunder the operating conditions in fiat-bed printing, i. e. in thepresence of water, unless the foils have been backed with a non-swellingbase.

The process of the present invention can also be applied to paper foilsor bases. A paper sheet having a hydrophilic surface with a minimum ofporosity is to be preferred. Thus, parchment paper foils oifer distinctadvantages. according to known methods. This can be done by treating thepaper with urea resins. Also paper foils having hydrophilic surfacelayers, which may be applied by means of a brush, can be used.

The expression foils having a hydrophilic non-metallic surface isbelieved to designate in the best manner all the abovementioned suitablebase materials. Foils backed with sheet metal are intended to beincluded.

Any known diazo compound which upon exposure to light decomposes into aprinting ink receptive substance may be used for producing the lightsensitive layer, however it is preferred to use the diazo compounds ofhigher molecular weight corresponding to the general formula R =an aryl,aralkyl, a higher alkyl or an aroyl residue,

Y==0, S, NH or NR1, R1 standing for alkyl, aralkyl or aryl,

Ar=an aromatic residue, and

X=an equivalent of an anion of an acid.

We understand the term aroyl to include in its scope the acyl radicalsof aromatic carboxylic acids, e. g. benzoyl. The expression equivalentof an anion of an acid is intended to designate radicals such as Cl",504 ZnCl4=, CsH5SO3 and the like.

The substituent Y and the diazo group N2 may preferably be in apara-position to each other. The aromatic residue Ar, the group R andthe NI-Lgroup may contain further substituents. In most cases it isadvantageous that the residues R and Ar are substituted by alkoxy, aroxyor N-aryl-sulfamido groups, or by one or more halogen atoms.

NA1'Nz-X as above defined (i. e. where Y=NR1) the substituents In thediazo compound of the formula i The paper base is preferably renderedwater-proof R and R1 can be connected with one another to form a highermolecular weight. The sulfonates of all the abovementioned diazocompounds, and their aldehyde condensation products respectively (whichsulfonates are to be prepared by acting upon a diazo compound with asulfite in a known manner), can also be used. Also useable are the diazoamino compounds obtained from the above named diazo compounds and theiraldehyde condensation products, respectively, as reaction products of atreatment with' amines under known conditions.

The light sensitive layers can be incorporated with the usual additionsin the diazotype process, e. g. with acids or stabilizing salts.

The invention may be illustrated by the following examples:

Example 1 A parchment paper sheet is coated with a 1% aqueous solutionof the diazo compound of 4-amino-1-(N-(2,3',4',6'-tetrachlorobenzyl))-aminobenzene and subsequently dried. Bymeans of a printing machine an image is transferred onto the sensitizedpaper foil and then the foil is coated with a solution, containing 75parts of water, 25 parts of dextrine and 1 part of phosphoric acid, toform a film covering the foil. When dry, the back surface of the foil isexposed to light. At all areas covered by the image the diazo compoundis decomposed to form a hydrophobic substance, that is the base for thefatty ink. This printing foil permits a great number of impressions tobe printed on flat and offset printing machines.

Example 2 Subsequently it is exposed to light on its back surface untilthe yellow color of the diazo compound has disappeared. Now water andfatty ink are applied to the foil and it can be used for printing in theusual manner.

Example 3 A superficially saponified cellulose acetate foil iscoat edwith an aqueous suspension of the diazo amino compound of 14-amino-1-[N-(2',6'-dichlorobenzyl)l-amino-benzene and guanidine, andthen dried. The diazo amino compound is prepared in a known manner fromsaid diazo compound'by acting upon it with guanidine nitrate in sodaalkaline solution. The light sensitive foil is provided with an image ina printing machine and coated with a film of mesquite gum, depositedfrom a 10% aqueous solution of mesquite gum which is applied to the foiland dried. The base for the fatty ink is produced by exposing the foilto light. Water and fatty ink are applied to the foil and the foilisthen ready for printing.

Example 4 and dried is provided with an image with the aid of atypewriter. A 10% aqueous solution of gum arabic .is

now applied to the sensitized side of the foil which is dried by meansof hot air and then exposed to light until the diazo compound isdecomposed, the fading of the diazo compound being a criterion of itsdecomposition. Preferably, the foil is exposed to light on its backsurface. Now the foil is mounted in an ofiset printing machine andwashed with water by means of a sponge. The foil is now ready forprinting.

Example 5 A cellulose acetate foil is saponified to a depth of 151.0 andcoated with a 2.5% solution of the condensation product prepared fromthe diazocompound of pamino-diphenylamine and formaldehyde. The excessof the solution is wiped off and the foil is dried. An image is appliedto the photosensitized foil by means of a printing process or alithographic pencil. Subsequently, the sensitive layer provided with theimage is coated with a 5% aqueous dextrine solution and exposed to lightto decompose the diazo compound. The rest of the procedure is the same,as has been described in Example 1, and positive prints are obtained.

Example 6 A paper foil is sensitized with a 3% aqueous solution of thesulfonate of the condensation product named in Example 6 and, afterhaving been dried, the foil is provided with an image by means of atypewriter. After a 4% aqueous solution of polyvinylpyrrolidone has beenspread on the foil it is dried and exposed to light on its back surfaceuntil the diazo compound fades. The remaining procedure is the same asthat described in Example 6, resulting in the production of positiveprints.

After having clearly described our present invention, we claim:

1. A process, for making printing material from photosensitive materialhaving a hydrophilic, non-metallic surface sensitized with a lightsensitive diazo compound which upon exposure to light decomposes into aprinting ink receptive substance, comprising the steps of mechanicallytransferring an image onto the photo-sensitive material, applying anaqueous solution of a water soluble organic colloid substance to thelight sensitive surface of the material and exposing the material tolight to transform the diazo compound not covered by said mechanicallytransferred image into a hydrophilic substance and to decompose thediazo compound covered by said mechanically transferred image into ahydrophobic printing ink receptive substance.

2. A process, for making printing material from photosensitive materialhaving a hydrophilic, non-metallic surface sensitized with a lightsensitive diazo compound which upon exposure to light decomposes into aprinting ink receptive substance, comprising the steps of mechanicallytransferring an image onto the photo-sensitive material, applying anaqueous solution of a water soluble organic colloid selected from thegroup consisting of gum arabic, cellulose ethers, polyuronic acids andtheir salts, dextrine, sugar, polyvinyl alcohol, polyvinyl pyrrolidones,water soluble urea resins, water soluble protein substances,polyethyleneoxide, pectin, sodium alginate, mesquite gum andmannogalactan to the light sensitive surface of the material andexposing the material to light to transform the diazo compound notcovered by said mechanically transferred image into a hydrophilicsubstance and to decompose the diazo compound covered by said mechanically transferred image into a hydrophobic printing ink receptivesubstance.

3. A process, for making printing material from photo sensitive materialhaving a hydrophilic, non-metallic surface sensitized with a lightsensitive diazo compound which upon exposure to light decomposes into aprinting ink receptive substance, comprising the steps of mechanicallytransferring an image onto the photosensitive material, applying anaqueous solution of gum arabic to the light sensitive surface of thematerial and exposing the material to light to transform the diazocompound not covered by said mechanically transferred image into ahydrophilic substance and to decompose the diazo compound covered bysaid mechanically transferred image into a hydrophobic printing inkreceptive substance.

4. A process, for making printing material from photosensitive materialhaving a hydrophilic, non-metallic surface sensitized with a lightsensitive diazo compound which upon exposure to light decomposes into aprinting ink receptive substance, comprising the steps of mechanicallytransferring an image onto the photosensitive material, applying anaqueous solution of mesquite gum to the light sensitive surface of thematerial and exposing the material to light to transform the diazocompound not covered by said mechanically transferred image into ahydrophilic substance and to decompose the diazo compound covered bysaid mechanically transferred image into hydrophilic substance and todecompose the diazo compound covered by said mechanically transferredimage into a hydrophobic printing ink receptive substance.

5. A process, for making printing material from photosensitive materialhaving a hydrophilic, non-metallic surface sensitized with a lightsensitive diazo compound which upon exposure to light decomposes into aprinting ink receptive substance, comprising the steps of mechanicallytransferring an image onto the photosensitive material, applying anaqueous solution of dextrine to the light sensitive surface of thematerial and exposing the material to light to transform the diazocompound not covered by said mechanically transferred image into ahydrophilic substance and to decompose the diazo compound covered bysaid mechanically transferred image into a hydrophobic printing inkreceptive substance.

6. A process, for making printing material from photosensitive materialhaving a hydrophilic, non-metallic surface sensitized with a lightsensitive diazo compound which upon exposure to light decomposes into aprinting ink receptive substance, comprising the steps of mechanicallytransferring an image onto the photosensitive material, applying anaqueous solution of polyvinyl pyrrolidone to the light sensitive surfaceof the material and exposing the material to light to transform thediazo compound not covered by said mechanically transferred image into ahydrophilic substance and to decompose the diazo compound covered bysaid mechanically transferred image into a hydrophobic printing inkreceptive substance.

7. A process for making printing foils useful in flat and offsetprinting, comprising mechanically transferring an image onto a foilhaving a hydrophilic non-metallic surface which is photosensitized bymeans of a diazo com pound of the group consisting of diazo compounds ofthe general formula RY-ArN2 X wherein R=a member of the group consistingof aryl, aralkyl,

higher alkyl and aroyl residues,

Y=a member of the group consisting of O, S, NH and NR1, R1 standing foralkyl, aralkyl or aryl,

Ar=an aromatic residue, and

X=an equivalent of an anion of an acid,

their aldehyde condensation products, the sulfonates and diazo aminocompounds of said diazo compounds and their aldehyde condensationproducts respectively, applying an aqueous solution of a water solubleorganic colloid substance to the light sensitive surface of the foil,and exposing the foil to light and washing it with water.

8. A process for making printing foils useful in flat and offsetprinting, comprising mechanically transferring an image onto asaponified cellulose ester foil photosensitized by means of a diazocompound of the group consisting of diazo compounds of the generalformula R=a member of the group consisting of an aryl, aralkyl,

a higher alkyl and aroyl residues, =a member of the group consisting ofO, S, NH, and

NR1, R1 standing for alkyl, aralykyl or aryl,

Ar stands for an aromatic residue, and

X: an equivalent of an anion of an acid,

their aldehyde condensation products, the sulfonates and diazo aminocompounds of said diazo compounds and their aldehyde condensationproducts respectively, applying an aqueous solution of a member of thegroup consisting of gum arabic, cellulose ethers, polyuronic acids andtheir salts, dextrine, sugar, polyvinyl alcohol, the polyvinylpyrrolidones, water soluble urea resins, 'water soluble proteinsubstances, polyethyleneoxide, pectin, sodium alginate, mesquite gum andmannegalactan to the light sensitive surface of the foil, exposing thefoil to light and washing it with water.

No references cited.

1. A PROCESS, FOR MAKING PRINTING , MATERIAL FROM PHOTOSENSITIVEMATERIAL HAVING A HYDROPHILLIC, NON-METALLIC SURFACE SENSITIZED WITH ALIGHT SENSITIVE DIAZO COMPOUND WHICH UPON EXPOSURE TO LIGHT DECOMPOSESINTO A PRINTING INK RECEPTIVE SUBSTANCE, COMPRISING THE STEPS OFMECHANICALLY TRANSFERRING AN IMAGE ONTO THE PHOTO-SENSITIVE MATERIAL,APPLYING AN AQUEOUS SOLUTION OF A WATER SOLUBLE ORGANIC COLLOIDSUBSTANCE TO THE LIGHT SENSITIVE SURFACE OF